Electromagnetic Acoustic Transducer (EMAT) is applied to nondestructive testing of aluminum-GFRP laminates. Because of its high specific strength, laminated FRP came to be used in place of metal materials. However, once delamination is introduced by the impact force in the out-of-plane direction, the compressive strength in the in-plane direction is greatly reduced. To improve the tolerance for impact force, fiber metal laminates (FML) have been developed. Since debonding may occur at the interface of FRP and metal sheet, nondestructive detection of the debonding is required as health monitoring of the FML. In this study, GFRP laminates were molded on aluminum sheets, and we measured the distribution of standing wave amplitude in the aluminum sheets using EMAT for shear wave. In the bonded area, the shear wave is partially transmitted to the FRP on reflection at the boundary, which makes the attenuation coefficient larger than that in the debonded area. It was found that in scanning the EMAT, the standing wave amplitude starts to change when the center of the EMAT passes the boundary between bonding and debonding areas. It was also revealed that minimum size of the debonding area that EMAT can detect is comparable to its effective area. For accurate evaluation of the debonding area, resonant frequency measurement is recommended at each point.

Since the wear of front-rod bearings of railroad switches induce the switch failure, wear evaluation is indispensable. On the other hand, the various parts of railroad switches are adjusted so as to avoid derailment. For example, the attachment position of the adjustment nut of switch adjuster rod could enlarge the contact force between tongue rail and stock rail. The extension of front rod is also used to eliminate the gap between the toe of tongue rail and stock rail. In this paper, the bearing wear during the switching operation is estimated by multi-body dynamics simulation. The effects of the attachment position of adjustment nut and the extension of front rod are also evaluated. When the switch moves rightward, the driving force of electric point machine is transmitted to switch rod through switch adjuster rod. Then, the force is transmitted to right tongue rail through right switch rod bracket which connects switch rod and right tongue rail. Although the attachment position of adjustment nut controls the contact force between tongue rail and stock rail, that does not change the path of force transmission and the force acting on the bearing. Therefore, the attachment position does not affect the bearing wear. On the other hand, the extension of front rod changes the path of force transmission. The most of driving force of electric point machine is transmitted to the left switch rod bracket, front rod and right tongue rail in order. Therefore, the increase in the force acting on the bearing increases its wear. In the case of 6 mm extension of front rod, the estimated amount of wear is 3.44 μm, which is 3 times larger than the case of no extension.

In recent years, the aging of power plants and other infrastructure facilities has become an issue. Therefore, a health-monitoring technology has attracted attention in order to ensure the integrity of structures. An inverse analysis is conducted to estimate the size and position of cracks in this technology. The accuracy of the inverse analysis is dependent on the form of the objective function and the optimization calculation method. Generally, optimization calculation methods using the gradient of the objective function is adopted. However, it is known to have the drawback that the search solution strongly depends on the initial value setting. The biomimetics-based cuckoo optimization algorithm (COA) is a method that can overcome this drawback. However, there are few examples of estimating the crack size and position in structures using the COA. In this study, an inverse analysis method is developed to estimate the crack angle and position of circumferential through-wall crack in pipes. In this study, transfer matrix method (TMM) was utilized to numerically calculate the deformation and rotation angle of the pipe, which are required in the inverse analysis. For this purpose, the fundamental theory of the TMM was extended to the element with a through-wall crack. Consequently, it was confirmed that the crack angle, position and magnitude of the applied shear load can be accurately estimated by the developed method.

The purpose of this study to derive a theoretical solutions for two elliptical inclusions that are perfectly bonded to an elastic medium (matrix) of infinite extent under antiplane loading. These two ellipses have different shear moduli, long-axial radii, short-axial radii, inclining angles, and central points. The matrix is assumed to be subjected to arbitrary antiplane loading by, for example, uniform shear stresses, as well as to a concentrated force and screw dislocation at an arbitrary point. The solutions are obtained through iterations of the Möbius transformation as a series with an explicit general term involving the complex potential functions of the corresponding homogeneous problem. This procedure is referred to as heterogenization. Using these solutions, several numerical examples are presented graphically.

Various fields, such as the paper industry, chemical engineering, and renewable energy, are faced with gas-liquid two-phase flows and are being studied by visualization and observation. Although it is necessary to quantitatively evaluate the characteristics of bubbles, there is a limitation in the amount of labor required for detection and measurement by human observation of images. There are no examples for bubbles in polymer electrolyte membrane water electrolysis (PEMWE), where the bubbles in PEMWE have heterogeneous backgrounds, unpatterned patterns, and unclear bubble contours. Existing methods for detecting these bubbles are not expected to be accurate enough. In this study, a deep learning-based bubble detection method using convolutional neural networks (CNN) was developed for bubbles in PEMWE. Our method has two novel approaches: first, we developed an algorithm that automatically draws a pseudo-bubble image based on an actual bubble image on an arbitrary background as a method for automatically generating training data for the CNNs. Second, we developed a CNN-based bubble detection method that uses the motion of bubbles, specifically, the difference between the bubble image and the image from one frame ago, as input. Finally, we tested the algorithm on bubble images in a PEMWE and achieved an F1 score of 0.83 or better for all current densities of 0.5, 1, 2, and 3 A/cm², and an F1 score of 0.844 for the entire detection.

Flow-Accelerated Corrosion (FAC) is a pipe wall thinning phenomenon to be monitored and managed in the power plants with high priority. Its management has been conducted with conservative evaluation of thinning rate and residual lifetime of piping based on wall thickness measurements. However, in the actual plants, noticeable case of the wall thinning occurred in branch and junction piping (T tube). There is a problem to manage the wall thickness of the part covered by reinforcing plate of the T tube, because measurement of this area is difficult to be conducted with ordinary ultrasonic testing devices due to the presence of the reinforcing plate. In this study, numerical flow analysis for the T tube was conducted, and the wall thinning profile due to the FAC was evaluated by calculating the mass transfer coefficient. It was found that a localized wall thinning distribution occurs in the area where the reinforcement plate of the T tube exists. And this tendency is affected by pipe geometry and Reynolds number. In previous studies, a model that functionalized by pipe geometry and Reynolds number was introduced to predict this wall thinning trend. In this paper, the effectiveness of the proposed decay function was confirmed by comparing it with measurements taken in actual plants. It was shown that the maximum wall thinning rate at the T tube junction, including below the reinforcing plate, can be evaluated conservatively within an appropriate range by making corrections to the proposed decay function that take into account the causes of variation in the actual data.

This study aims to locate defects in polymer electrolyte fuel cells (PEFCs) caused by electrolyte breakage, electrical contact failure, contamination of electrical insulators, or the like in an easy and instantaneous manner by a noninvasive method. Specifically, the density of the magnetic flux generated around the PEFC during power generation is measured, and then value of the electric current in the electrodes of the PEFC is estimated from the magnetic flux density through inverse problem analysis using sparse modeling. Since the estimated current values are affected by the variables used in the inverse problem analysis, the procedure for determining the variables was first discussed using a simulated fuel cell that imitated the current flow inside the fuel cell. Then, the authors tried to detect a defect of 10 mm x 10 mm inside the fuel cell containing one layer of MEA (Membrane Electrode Assembly) with electrode area of 50 mm x 50 mm according to the above determination procedure. Each estimated current at the three characteristic defect locations was 0.00 A, and the estimated current values at other locations were higher than 0.08 A. From this current distribution, the location of the defect was able to be clearly identified. Particularly, it became possible to detect defects at the central part of the electrode, which was impossible with the Tikhonov regularization method.

An experimental study was conducted on the effect of the shape of the fuel nozzle outlet on the suppression of soot emission from a coaxial flow diffusion flame. Three nozzle shapes were used, namely circular, square, and an equilateral triangle. Propane was used as the fuel and air as the oxidizer. The fuel flow rates Q_f were 2, 3, and 4 cm³/s. At the maximum Q_f of 4 cm³/s, the nozzle shape changed the soot discharge characteristics and the flame structure. The soot discharge was suppressed the most with the triangular nozzle and the least with the circular nozzle. The shape of the soot concentration distribution near the flame tip was similar to the nozzle shape, indicating that the influence of the nozzle shape reached the flame tip. Soot formation started earliest in the triangular nozzle and latest in the circular nozzle. In non-circular nozzles, soot started to form from the downstream regions of the corners of the nozzle rims. This is because the profile of the fuel flow was close to the flame front in these downstream regions. Soot oxidation was fastest in the triangular nozzle and slowest in the circular nozzle. Therefore, the flame was the lowest in the triangular nozzle and the highest in the circular nozzle. The oxidizer flow velocity toward the flame base was high in the downstream region of the flat side of the non-circular nozzles. The velocity was especially high in the triangular nozzle, and the CH radical emission, which is closely related to the heat release rate, was also strong at the flame base. As mentioned above, the fuel concentration distribution, the convective transport of the oxidizer, and the flame structures changed in the non-circular nozzles, and in particular, soot emission was suppressed in the triangular nozzle.

Focusing on the correlation between speech sounds and body movements, we developed a voice-driven embodied entrainment character called InterActor that automatically generates communicative motions from speech, and demonstrated the effectiveness of the system. We also developed a communication agent that responds appropriately to utterance contents by focusing on words in speech using speech recognition. However, these systems simply generate body motions from the burst-pause of speech. The response actions corresponding to speaker’s speech speeds were not considered. In this paper, we analyze the relationship between an individual’s speech activity and speech speed[mora/s] from various speech experiments with the aim of facilitating speech according to speaker’s speech characteristics. We develop a voice-driven embodied entrainment system which performs nodding with different speeds according to speech speeds based on speech recognition. Based on the results of the speech experiments, we conduct an online evaluation experiment using videos of multiple speakers with different speaking speeds using the robot as a platform to verify the effectiveness of the response actions generated by the system.

This paper deals with applications of data-driven control, which is a controller tuning method that directly utilizes the data, for mechanical systems. Particularly, we focus on the valve opening control of the motor-operated valve as one of the representative mechanical control units which are used in much industrial equipment and are needed to be precisely controlled. If we have a mathematical model of such a system, a model-based controller design is the most rational approach. Otherwise, data-driven controller tuning is also expected to be a rational approach. However, there exists a nonlinear characteristic, such as the limit of a speed implemented in the nonlinear compensator. Since conventional data-driven controller design can not be used because data-driven control is generally derived for only linear time-invariant systems, we have to modify the method of driven controller tuning method so as to be applicable for such systems. This paper proposes a controller tuning method for the valve-opening control system implemented as a cascade control system with a limit of the speed. Here, we apply Virtual Internal Model Tuning, which is abbreviated as VIMT, to tune the inner linear controller. Then, we also apply data-driven prediction to compute the outer loop controller including the limit of the speed. Finally, we verified the usefulness of the proposed method using experimental verification.

In this paper, mechanism of compliance steers for lateral force and self-aligning torque is studied for strut type front suspension, which is commonly used in front wheel drive vehicle with transverse engine. First, through qualitative consideration, it is clarified that both of the compliance steers for lateral force and self-aligning torque consist of changes in toe-angle of three modes. Mode I is the change in toe-angle due to difference of displacements of the points on steering knuckle. Mode II is the change in toe-angle due to rotation of the lower arm. Mode III is the change in toe-angle due to displacement of the upper support of the suspension. In addition, it is shown that effects of design specifications of the suspension on the modes of compliance steer for lateral force and those for self-aligning torque are different. Based on this consideration, guidelines for design of strut type front suspension in terms of compliance steers for lateral force and self-aligning torque are presented. Then, CAE analysis for a suspension model based on a commercial vehicle is performed to confirm validity of the qualitative consideration as well as to show that compliance steer for self-aligning torque can have significance greater than that for lateral force.

In this paper, we considered how the kingpin axis transitions due to the turning lateral force acting on the front wheels of a turning vehicle. Two types of consideration were conducted: qualitative consideration and quantitative consideration using CAE. In the qualitative consideration, we discussed the transition of the kingpin axis due to the elastic characteristics of the suspension when there is no artificial steering, that is, when only the turning lateral force acts on the front wheels. As a result, it was clarified that the caster angle and the caster trail of the kingpin axis increased due to the elasticity of the suspension. Next, in the quantitative consideration, we discussed the transition of the kingpin axis when the steering angle and turning lateral force acting simultaneously on the front wheels and suspension, assuming a lane change at high speed. For the steering angle and turning lateral force, the values in an actual high-speed lane change were used. As a result, We clarified that the caster angle and the caster trail of the kingpin axis are decreased. And then the kingpin angle and the kingpin offset are increased during the initial steering of a high-speed lane change about the strut type front suspension, which is commonly used in front wheel drive vehicle with transverse engine.

For industrial welding robots using the teaching-playback method, repeatability is more important than absolute accuracy. However, when a robot is replaced due to failure or other reasons, the tip position is shifted because the error factors related to tip positioning are different between the robot before and after the replacement. This can impede recovery. To overcome this problem at production sites where industrial robots are used, easy measurement without the use of expensive sensors is required. On the other hand, when the robot is replaced with another robot of the same model, the mechanical errors such as joint stiffness, arm stiffness and link length error are almost the same and their difference can be assumed to be extremely small, but the joint origin error remains as an individual difference and its effect on the tip misalignment is not small. Therefore, it is the joint origin error that has a large influence on tip misalignment as an individual difference. In recent years, inexpensive devices with high image resolution, such as consumer-use cameras and smartphones have become available at low cost and their use is effective to reduce tip misalignment caused by individual differences in robots at manufacturing sites. In this paper, we focus on the sensitivity of the tip position error with respect to the joint origin error and propose a method to estimate the joint origin error by designing a trajectory in which the tip error is magnified so that the joint origin error can be easily measured using movies of the tip position taken by a digital camera. We verify the effectiveness of this method using an experimental robot.

In this paper, we propose a simulation method to evaluate the packed state of catalyst pellets in a pipe reactor for gas phase reaction. This simulation method is based on dynamic explicit FEM (finite element method) and consists of three steps. Specifically, first, the catalyst pellets freely fall under gravity and flow into a packing hose with a hopper-like inlet. Then, after the catalyst pellets reach the bottom of the pipe reactor, the packing hose is pulled up to create a random packing of the catalyst pellets in the pipe reactor. Finally, the bulk density and stress distribution of the catalyst pellets randomly packed in the pipe reactor are calculated, and the packed state of the catalyst pellets is evaluated. Using this simulation method, we simulated the packing of cylindrical catalyst pellets into the pipe reactor and evaluated the packed state of the catalyst pellets in the pipe reactor. As a result, it is clarified that the maximum equivalent stress generated at the bottom of the catalyst pellets packed in the pipe reactor approaches a constant value as the ratio of the packed height of the catalyst pellets to the diameter of the pipe reactor increases. In addition, the effects of the shape of the catalyst pellets on the bulk density and average equivalent stress of the catalyst pellets in the pipe reactor are elucidated, and the optimal shape of the catalyst pellets that can increase the bulk density and reduces the stress is found. The optimally shaped catalyst pellets are expected to improve their packed state in the pipe reactor, extend the durability of the catalyst pellets and increase the efficiency of production. In this paper, it is assumed that the packed state and durability of the catalyst pellets are evaluated based on the bulk density and stress distribution of the catalyst pellets in the pipe reactor.

In the manufacturing industry, the transfer of knowledge of expert is an issue because the number of experts is decreasing. In order to support knowledge transfer, various support systems have been developed. However documenting knowledge and determining the level of system users is a concern. This study aims to develop a technique for knowledge extraction and user level judgement using gaze measurement. In order to develop these techniques, the difference of gaze between expert and beginner need to be evaluated. In this study, the gaze of experts and beginners were measured in relation to the vortex exploration skill in the task to explore for vortices which is a typical phenomenon from fluid simulation results. 6 fluid simulation result pictures were presented to experts and beginners, and their gaze was measured. Our result suggested that the expert observe vortex area and area without vortex long time. Beginner did not observe the horizontal elliptical vortices many times, as a result they often missed it. Beginner’s gaze transfer between vortices area many times than expert’s. Expert’s pupil size was larger than beginner’s. These results imply that the experts observe the simulation result image widely, find a place where there is a possibility of a vortex, and concentrate long time to judge whether it is a vortex. On the other hand, the beginners find a place where there is a possibility vortex in the simulation result image and compare other area where there is a possibility vortex to judge whether it is a vortex. By utilizing the gaze measurements, the method of exploring the vortex of the experts was revealed and it was found that user’s level can be judged.

A cycloidal planetary reducer, which fulfils both high reduction ratio and low vibration in a thin and small body, had been proposed to cope with the further downsizing of DC motors. The reduction mechanism is inspired by the intellectual toy ‘Spirograph’ and structurally based on a planetary reducer. Instead of the internal gear of the planetary reducer, output plate with skid epitrochoid groove is introduced. The sun gear is connected to the input shaft and the planetary carrier works as a stator. The planetary gear has a pin that fits in the groove of the output plate. According to the rotation of the planetary gear, the output plate revolves in the counter direction with a speed in inverse proportional to the number of the skid epitrochoid. The prototype can realize higher reduction ratio compared to the planetary reducer without unpleasant vibration that is unavoidable in the cycloidal reducer. It is confirmed that the idling torque is very small with 0.006Nm, and the torque transmission efficiency is acceptable with 73%. But the torque fluctuation caused by the cam motion by the pin and groove is remarkable, which will be forthcoming challenges.

In the present paper, a method to evaluate the occlusal state and occlusal morphology that can integrate an optimal occlusal force field under clenching is proposed using simplex optimization and principal component analysis (PCA). The objective function of the optimization is taken as a sum of the weighted occlusal forces and reaction on temporomandibular joint (TMJ) to maximize the former and to minimize the latter. The optimized solutions in the region defined by the combination among three kinds of muscle forces were obtained by two-step simplex method, and the subregion with no reaction of TMJ was summarized as a ratio to the whole region, newly defined here as a good balance ratio. As a result of PCA of total 528 samples of the good balance ratios for 13 different muscle force combinations, two principal components (PCs) are enough to represent the optimized masticatory system. The first PC suggests the ideal state of occlusion and the second one implies the characterization of combination among muscles. From the consideration of PCA, with the wider equalizer angle, the easier it is to support the force of the temporalis muscle in an ideal occlusal position, and the more the occlusal contact point is shifted backward, the harder it is to support the force of the temporalis muscle. Comprehensively, the proposed good balance ratio becomes the effective quantity to evaluate the ideal masticatory system with the optimized occlusal force field for the statistically reduced indexes showing the combination of muscles.

It is shown that only inherently safe design measure, which is defined in ISO 12100 as protective measure which either eliminates hazards or reduces the risks associated with hazards by changing the design or operating characteristics of the machine without the use of guards or protective devices, can eliminate hazards or reduce the severity of risks. However, mechanical designers actually apt to use safe guards and other measures because they do not have concrete design methods to apply them. In the consequence the machine does not have adequate inherently safe design measures. This paper proposes the process of scheme design for newly designed machinery to adhere adequate inherently safe design measures and other safe measures. Scheme design process consists of four stages, required specification definition, function definition, component and mechanism choice and structure design. These four stages are in order of consideration. The 14 items of inherently safe design measures those are classified according to their contents are shown in ISO12100. And each of them is suitably assigned to each stage of design process according to its content. Each stage study is narrowed down and clarified by this assignment. This process is proceeded in the matrix table to get adequate and less omission design by comparing and evaluating various ideas that can be thought of. By this proposal, front loading design process is implemented and the machinery design will obtain adequate inherently safe design measures and other safety methods.